A power semiconductor device for handling relatively high electric power mainly from several hundred kilowatts to several megawatts may be used in an inverter circuit for an industrial motor, an automotive motor, and the like, a power supply for a large-capacity server, an uninterruptible power supply, and the like. Examples of the power semiconductor device include a semiconductor switch such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor). As the IGBTs, while planar gate IGBTs have been widely used conventionally, vertical IGBTs using a trench gate making high integration possible have recently come to be used.
In order to further increase a current handled by such an IGBT using a trench gate, for example, according to Japanese Patent Laying-Open No. 2007-273931 (Patent Literature 1), a power semiconductor element (power semiconductor device) includes an emitter plug, and an emitter pad connected to the emitter plug.
Electrical connection to the pad as described above is performed, for example, by wire bonding. On this occasion, a transistor may be damaged by an impact received by a portion immediately below the pad. This is mainly due to miniaturization of the size (an interval, dimensions, a film thickness, and the like) of parts in accordance with high integration. To suppress such damage, for example, according to Japanese Patent Laying-Open No. 2006-324265, a semiconductor device is characterized in that a plurality of conductive layer wiring metals and interlayer insulating films are alternately stacked immediately below a pad, the conductive layer wiring metals adjacent with an interlayer insulating film sandwiched therebetween are connected through a via, the stacked layers are divided into a plurality of fine layers made of a different interlayer insulating film material, and a via formed in an interlayer insulating film formed above an interface between the interlayer insulating films made of different materials has a diameter greater than that of another via.